Notwithstanding my previous comment, Norwegian are legislatively required to provide training to the crews on the aircraft they operate. A training bond is NOT enforceable as the training is not voluntary, it is mandatory. Norwegian cannot recover a loss as none has occurred due to the mandatory requirement.
Furthermore, the agency is the employer and leases its employee crew to various airlines. If the airline, Norwegian, is required to provide training to the contractor, it is not the responsibility of the contractor to pay the leasing airline for that training.